Hi, everyone. This is my first posting and I've got an interesting situation.


I installed 5, 5 gallon, Pinyon Pines and 3, 15 gallon, Italian Cypress trees at a home in 29 Palms, CA, this spring. Both trees are growing in the area and seem to be doing just fine. I amended the soil (sandy) with about 20% Fox Farm soil amendment so that it would hold a bit of moisture for the new roots. All the holes were dug about 3X the diameter of the root balls but no deeper. Water application is controlled by a timer and applied using 0.6 gph inline emitters in both an "X" across the root ball and a circle under the drip line. Watering is once per day for 30 minutes and this means each tree is getting around 5+ gallons per day. The cypress trees actually have a little more drip line around them, so they get a bit more water plus they are mulched around the base. The pines have no mulch. There is a little bit of puddling when the emitters are running, but no real runoff. Everything seems to be going straight down into the soil.


Question 1: Are the trees getting enough water for full sun in 100+ weather?


Now, it gets strange. The homeowner decided that since it was hot, the trees needed more water. She did not mention anything about needle drop, or browning, or sagging branches - just that she felt they weren't getting sufficient water. The watering schedule is now 4X per day for a total of around 90 minutes of run time!


Question 2: Is this over-watering? If so, can it damage the trees?


My concerns are that the trees can actually suffer from too much water given they are adapted to dry climates, and with so much water there is no incentive to start sending their roots out wide and deep for the future. I have advised the homeowner that I disagree with what she is doing, but it seems the neighbor across the street is now advising her. I'm hoping she will listen to people who know how to garden.


Thanks for your help.


Rolf

Welcome to the site!
Moving your question to the Trees and Shrubs forum

It's been my experience that the home owners usually listen to the people who tell them what they want to hear.
(confirmation bias)

It sounds like a lot of water to me for desert adapted trees... But... I wouldn't have waited until spring to plant. Around here, Autumn is when we plant... too hot too fast for spring plantings...

I googled 29 Palms...
Out by Joshua Tree National Park... Really wouldn't expect either of these trees to be suitable...

I've seen pinion growing as naturals in the New Mexico mtns... but out in the desert? Seems iffy.

How is the home owner allowed to use this amount of water?

Sorry... more questions than answers.

From Calscape: "Pinus monophylla grows in areas that receive between 8 and 18 inches of precipitation (Zouher 2001), and can grow for 350 years, but most are younger than 150 years. They are considered the most drought tolerant of all pines."

Although native to somewhat higher elevations east of the Sierra Nevada, the pines are commonly grown in lower, high desert areas, so I don't think suitability is an issue, except insofar as California's climate is rapidly changing.

It's frustrating when inexperienced growers believe "if a little is good, a lot is better." I have a neighbor who heard about the advantages of mulching and now mulches his landscape trees six inches up the bark. I've learned to ignore his yard, but in your case, you installed the trees and have a stake in the game.

It's difficult to assess your watering schedule without knowing more about the soil and surrounding conditions. You describe it as sandy — that could work to your advantage in avoiding overwatering, except for the unfortunate decision to add water-retaining amendments to the planting hole. However, that does sound like a lot of water, or at the very least, too frequent.

New trees do need extra water for the first year or more, especially in blazing weather, but it's really hard to prescribe a strict "water x gallons x times a week" without accounting for endless variables. It is never recommended to allow the roots to remain constantly wet. Four times a day never allows the soil to reoxygenate. The soil amendments can also be impeding free drainage. Did you do a drainage test before planting? Other than the amendments, did you follow best practices for spreading roots and flair depth? It sounds like you do have experience, yet, like Stone, I've got more questions than answers because there is more to the survivability of these trees besides the amount of water they're getting. But drowning them is a surefire way to kill them fast and you clearly understand that!

Unfortunately, arguing to your homeowner that a bunch of people on a gardening website in other parts of the country disagree with her watering theory probably isn't going to convince her, although it might encourage you to take a firmer stance and seek other resources. Find some local authorities — tree farm owners, UC extension services, certified arborists, water agency guidelines — and get the facts specific to your area to present to her.

Maybe send her this article. It's a good explanation of why overwatering is bad
https://www.natesnursery.com/p....

https://ucanr.edu/blogs/UCANRC...

Although based on Portland, here is a good guide
https://friendsoftrees.org/blo....

Thank you for this info. It is helpful to me, but not sure if the homeowner will listen. All I can do is try.

The soil is pretty much pure sand and it drains quickly. I had not thought of that actually saving the trees. As for the pinyon pines, they grow in the nearby national park and others in the neighborhood are successfully growing the Italian Cypress. If I continue with this project, I will definitely install other plants in the fall.

Thanks again.

Rolf

The sand is saving the trees, but it really IS too much water. The original schedule was too much as well. Even here, either Pomona or Riverside, we water at most 3 times a week and for those species in that location it would be fine too. Suggest that she check the soil moisture by digging down a couple of inches next to an emitter. If it is AT ALL moist she does not need to water.